Electrochemical Analysis of Film Forming Mechanisms Relevant to Data Storage Chemical Mechanical Planarization

With the rapid increase of data storage density, the operation distance between read/write head and media has fallen into the nanometer regime. This requires an atomic level planarization to avoid defects on the surface and  “crashes” of the read/write head media. Chemical mechanical polishing (CMP) has been selected to produce high quality surface finish on a Nickel Phosphorous (NiP) plated substrate, through the removal of a metal complex film formed on the surface. CMP is a process that balances the kinetic/ thermodynamic reactions between the formation of a chemically modified layer and its interaction with the slurry. In order to understand the mechanistic CMP film forming process, electrochemical techniques were developed to probe the impact of organic additives on the surface redox and film forming mechanisms. More specifically, through monitoring the OCP (under abrasive and nonabrasive conditions) versus time, the film removal rate and passivation film formation kinetics can be determined as a function of slurry additives. Using OCP, the film passivation of the metal slurry complex on the surface of a nickel electrode can be monitored as a function of polishing time and related to the film forming mechanism of the CMP process.